Biology 7.3

Front 1

Molecules have a type of energy called _______ motion.

Back 1

thermal aka heat

Front 2

What is diffusion?

Back 2

the movement of molecules of any substance so that they spread out evenly into the available space.

Front 3

True or False: During diffusion, each molecule moves randomly.

Back 3

True. Though diffusion of a population of molecules may be directional.

Front 4

__________ is met when two solutions have as many molecules crossing the membrane each second in one direction as in the other.

Back 4

Equilibrium

Front 5

True or False: In the absence of other forces, a substance will diffuse from where is it less concentrated to where is it more concentrated.

Back 5

False. a substance will diffuse from where is it more concentrated to where it is less concentrated

Front 6

What is a concentration gradient?

Back 6

the region along which the density of a chemical substance decreases.

Front 7

True or False: Work must be done in order to make substances diffuse down their concentration gradient.

Back 7

False. Diffusion needs no input of energy.

Front 8

True or False: Diffusion is a spontaneous process.

Back 8

True. No energy is needed for diffusion

Front 9

True or False: One substance is affected by the concentration gradient of another substance.

Back 9

False. Each substance diffuses down its OWN concentration gradient and no other.

Front 10

The diffusion of a substance across a biological membrane is called _____________.

Back 10

passive transport

Front 11

What is passive transport?

Back 11

The diffusion of a substance across a biological membrane.

Front 12

Why is passive transport named that?

Back 12

Because the cell does not have to expend energy to make it happen

Front 13

What drives diffusion?

Back 13

Concentration gradient

Front 14

The concentration gradient represents what type of energy?

Back 14

potential energy

Front 15

What is osmosis?

Back 15

the diffusion of water across a selective permeable membrane

Front 16

True or False: The movement of water across a cell and its environment is important to organisms.

Back 16

True

Front 17

What is the concept of tonicity?

Back 17

the ability of a solution to cause a cell to gain or lose water.

Front 18

What two factors are taken into account in the concept of tonicity?

Back 18

solute concentration and membrane permeability

Front 19

If there is a higher concentration of nonpenetrating solutes outside a cell in a surrounding solution, will water tend to leave or enter the cell?

Back 19

leave

Front 20

If there is a lower concentration of nonpenetrating solutes outside a cell in a surrounding solution, will water tend to leave or enter the cell?

Back 20

enter

Front 21

What does isotonic mean?

Back 21

an environment that is the same as the cell

Front 22

How will the net movement be if an animal cell is placed in an environment that is isotonic?

Back 22

no net movement

Front 23

How will the water movement be if an animal cell is placed in an environment that is isotonic?

Back 23

water flows across the membrane, but at the same rate in both directions

Front 24

True or False: In an isotonic environment, the volume of an animal cell is unstable.

Back 24

False. In an isotonic environment, the volume of an animal cell is stable.;

Front 25

What does hypertonic mean?

Back 25

More (referring to nonpenetrating solutes)

Front 26

How will the water movement be if an animal cell is placed in an environment that is hypertonic?

Back 26

The cell will lose water to its environment.

Front 27

What will happen to the cell if it is placed in a hypertonic environment?

Back 27

It will probably shrivel and die.

Front 28

How will the water movement be if an animal cell is placed in an environment that is hypotonic?

Back 28

Water will enter the cell faster than it leaves, and the cell with swell and lyse (burst)

Front 29

What exactly happens to a cell that lyse?

Back 29

it bursts like a balloon

Front 30

What is osmoregulation?

Back 30

the control of water balance

Front 31

____________ is the control of water balance.

Back 31

osmoregulation

Front 32

When the wall of a plant cell is described as turgid, what do we mean?

Back 32

very firm

Front 33

A plant cell is kept turgid by which surroundings: hypotonic, isotonic, or hypertonic?

Back 33

hypotonic

Front 34

A plant cell is flaccid by which surroundings: hypotonic, isotonic, or hypertonic?

Back 34

isotonic

Front 35

What happens to a plant cell that is placed in a hypertonic surroundings?

Back 35

It will lose water to its environment and shrink.

Front 36

What is plasmolysis?

Back 36

When a plant's plasma membrane pulls away from the wall.

Front 37

What is facilitated diffusion?

Back 37

When polar molecules and ions diffuse passively with the help of transport proteins that span the membrane.

Front 38

Ion channels function as _____ channels.

Back 38

gated

Front 39

____ channels open or close in response to a stimulus.

Back 39

gated

Front 40

For gated channels to respond, what two types of stimulus must it have?

Back 40

electrical or chemical

Front 41

True or False: If a gated channel is reacting to a chemical stimulus, the stimulus comes from the substance that is being transported.

Back 41

False. The stimulus is a substance other than the one to be transported.

Front 42

How do you think a cell performing cellular respiration rids itself of the resulting CO2?

Back 42

Because Co2 is nonpolar, it can diffuse through the plasma membrane. It must diffuse away so the concentration remains low outside the cell. concentration gradient.

Front 43

In the supermarket, produce is often sprayed with water. Why does this make vegetables look crips?

Back 43

The water is hypotonic to the plant cells so they take up water and the cells of the vetable remain turgid, rather than plasmolyzing.